Thanks for starting to write this blog post, David! I'll try to help you with point 2 on your first list. But for now, your second list:

1) For the blog, it's always better to have multi-part figures stacked vertically, so they can be as big as possible on the blog. The blog is just 450 pixels wide, so something like

`
`
``
`
`

is a good way to format images files.

2) Yes, you can now use either html or markdown for blog articles on wordpress, whatever you prefer! Try not to push your use of either system to the maximum extreme of sophistication...